SU1705396A1 - Cast iron - Google Patents

Abstract

This invention relates to metallurgy, in particular to wear resistant l. cast iron The purpose of the invention is to improve the performance properties. Cast iron containing carbon, silicon, manganese, chromium, nickel, molybdenum, aluminum, copper, tin, calcium and iron, additionally contains cerium, titanium carbonitrides, niobium nitrides and lanthanum in the following ratio, wt.%: Carbon 3, 4-3.8; silicon 2,4-2,8; manganese 0.8-1.5; chromium 0.3-0.7; Nickel 0.6-1.3; molybdenum 0,2-0,8; aluminum 0.1-0.4; copper 0.1-0.8; tin 0.002-0.015; cerium 0.02-0.08; titanium carbonitrides 0.02-0.25; calcium 0.02-0.05; niobium nitrides 0.03-0.1; lanthanum 0.02-0.07; iron else. 2 tab. 8 WITH

Description

The invention relates to the search for gray wear-resistant cast irons, which are working under conditions of wear and complex stress state, in particular for the manufacture of cylinders and sleeves of internal combustion engines with increased operational durability. Known cast iron containing, wt.%: Carbon 2.8-3.8 Silicon. Up to 0.9 Manganese Up to 0.9 Chromium 0.25-5.0 Molybdenum 0.30-5.0 Copper Up to 0.5 Phosphorus 0.1-1.0 Sulfur 0.01-0.1 Aluminum 2.5 -4.0 Iron Else

This cast iron has increased chill, low ductility, damping ability and operation- P ny resistance.

Also known cast iron of the following chemical composition, wt.%: Ј $

Carbon

Silicon

Manganese

Nickel

Chromium

Vanadium

Titanium Iron

1.8-2.5

0.4-0.6

5.0-10.0

0.1-2.0

0.5-2.0

0.2-0.4

0.03-0.1 Else

Known cast iron has insufficient stability of mechanical and operational properties.

31705396 Closest to the proposed

is cast iron, Carbon Silicon Manganese Chromium Nickel Molybdenum Phosphorus Copper Calcium Tin Aluminum Iron

containing, wt.%:

2.7-3.2

1.2-2.0

0.7-1.2

0.3-0.5

0.6-1.2

0.3-0.6 0.02-0.15 0.30-1.2 0.01-0.08 0.02-0.1 0.05-00, Rest

The physical and mechanical properties of this cast iron are as follows:

Tensile strength

with bending, MPa 8 0-930

Corrosion fatigue limit

MPa315-375

Depreciation, mg / 100 h 51.2-61, C

Damping

ability 51, 0-60

Cavitational operation

resistance, h 63-75

The disadvantages of this cast iron are low performance properties in conditions of cavitation, complex stress and wear.

The purpose of the invention is to increase the operational PROPERTIES.

The goal is achieved by the fact that cast iron containing carbon, silicon, manganese, chromium, molybdenum, copper, nickel, aluminum, phosphorus, tin, calcium and iron, additionally contains rare earth metals, titanium carbonitrides and niobium nitrides in the following ratio of components, mas

-

ten

:

15

20

25

The choice of the boundary limits of the components is determined as follows.

Additional introduction of rare earth metals (cerium 0.02-0.08 wt.% And lanthanum 0.02-0.07 wt.%) Is due to their high chemical and modifying ability, the ability to strengthen the matrix, crush the structure, improve the shape of graphite and increase mechanical and operational properties. At the same time, lanthanum has a greater effect on the elastoplastic properties and damping capacity, and cerium strengthens the matrix, increases the resistance to wear, durability and performance properties. With an increase in their concentration above the upper limits, the waste and chillbone of the pig iron increase and the stability of the damping capacity and performance properties decreases. When the concentration of cerium to 0.02 wt.% And lanthanum to 0.02 wt.% Their modifying and stabilizing effect is insufficient, and the mechanical and operational properties of cast iron are low.

Titanium carbonitrides reduce chill, accelerate the processes of graphitization and bainite transformation, crush the structure and increase the damping capacity and performance properties. With the introduction of them in an amount of up to 0.02 masd, the grinding of the structure and the increase in mechanical and operational properties is insignificant, and with an increase in their concentration more than 0.25 May. structure homogeneity, mechanical and operational properties are reduced.

The introduction of niobium nitrides is due to its high microalloying effect on the structure while stabilizing the elastoplastic and operational properties. Their influence begins to manifest itself at a concentration of 0.03 masD, and with an increase in the niobium nitride content of more than 0.1 wt.%, The number of non-metallic inclusions at the grain boundaries increases and the elastic-plastic and operational properties decrease.

Calcium is introduced as an effective modifier that cleans the grain boundaries from non-metallic inclusions and increases the stability of the structure and performance properties. The upper limit of calcium concentration is due to its limited solubility in pearlite, and at its concentration to

thirty

35

YU

50

55

5170

0.02 ma.I modifying effect is insufficient.

The introduction of 0.3–0.7 masD of chromium and 0.002–0.015 wt.% Tin into the cast iron micro-alloys the structure, improves the distribution of graphite and non-metallic inclusions, increases the density of the cast iron and resistance to wear and cavitation, which improves performance properties. The nicking effect begins to manifest itself at a concentration of 0.3 mW of chromium and 0.002 May. tin. With an increase in their content above the upper limits, chill is increased and the elastoplastic and performance properties are reduced.

The content of the main components (carbon 3, -3.8 us.%, Silicon 2.1 and 2.8 masD and manganese 0.8-1.5 May.4) was determined experimentally with regard to the practice of production of wear-resistant cast irons with enhanced characteristics of cavitation resistance and damping ability. Increasing their content above the upper limits reduces the homogeneity of the structure and the stability of the mechanical and operational properties. When their concentration is less than the lower limits, the process of graphitization deteriorates and the characteristics of damping ability, plastic and operational properties decrease. With a decrease in carbon content of less than 3, b sat and silicon of less than 2.1 sat. And an increase in manganese concentration of more than 1.5 wt.% And chromium more than 0.7 may. chill is significantly increased, areas of cementite are formed in the structure during casting in the chill mold, and the mechanical and operational properties, stability of structures and properties are reduced.

Phosphorus is excluded from the composition of cast iron, since it reduces the structural stability and damping capacity, the limit of bending endurance and plastic properties.

Molybdenum (0.2–0.8 masD), copper (0.2–0.8 masD), and nickel (0.6–1.3 wt.%) Strengthen the metal base and increase the mechanical properties and cavitation-operating resistance. . Increasing the content of these alloying components above the upper limits reduces the homogeneity of the structure, the damping capacity and the operational durability. When the concentration of their lower limits yn

five

0

five

five

0 0

45

Stretching the metal base and improving wear resistance and performance properties are insufficient.

The introduction of aluminum into the melt is based on its high affinity for oxygen and sulfur and the effective microdoping effect, which stabilizes the physicomechanical and operational properties. Its lower limit (0.1 wt.%) Is due to a marked increase in the stability of the structure, mechanical and operational properties, starting with this concentration. With an increase in the concentration of aluminum more than 0, May. the content of nonmetallic inclusions in the structure increases and plastic and operational properties decrease.

The cast iron is smelted in open induction furnaces. As scrap materials, steel scrap, electrodes bashing, chips, cast iron, briquettes of niobium nitrides and titanium carbonitrides, ferroalloys, microalloying and modifying additives are used. Ferromolybdenum, nickel and ferrochrome are introduced into the electric furnace, and crushed briquettes of niobium nitrides and titanium carbonitrides, ferrocerin, tin, lanthanum and other modifying additives are introduced into the ladle with the production of cast iron with a temperature of 1 ° C – 1500 ° C

In tab. 1 shows the chemical composition of the cast iron experienced bottoms.

Castings of cylinder liners are produced by a method of casting in a chill mold, and samples for mechanical testing are made into sand-clay molds. Castings and specimens are subjected to heat treatment - isothermal aging at 350-1 10 ° C.

In tab. 2 shows the mechanical and operational properties.

Flexural strength, corrosion fatigue limit and damping capacity are determined on specimens cut from test otli. wok according to GOST 7293-85, and the operational durability in case of cavitation and durability - on cast iron, cast in a chill mold. Chill size is determined on wedge samples.

five

As can be seen from the table. 2, the proposed cast iron possesses higher indices of operational durability at cavitation, wear resistance and damping ability than the known one.

five

Claims (1)

 17053 Claim Formula Cast iron containing carbon, silicon, manganese, chromium, nickel, molybdenum, aluminum, copper, tin, calcium and iron, characterized in that, in order to improve performance, it additionally contains cerium, titanium carbonitrides, niobium nitrides and lanthanum in the following the ratio of (0 relative components, wt.%: Carbon3, -3.8 Silicon 2.4-2.8 Manganese 0.8-1.5 one Table. one 75 3.2 372 506 528 512 11.8 12.6 12.2 672 708 702 17053961 ° Continued table. 2 528 512 112 3.8 9.8 378 565